This invention relates in general to transporting of vehicles by a mass transport system and in particular to a system that will magnetically levitate transporting vehicles.
In U.S. Pat. No. 6,039,135, issued Mar. 21, 2000, a mass transport system is shown that utilizes a pair of guideways. Each guideway has a shroud surrounding it with a slot for receiving an axle of a vehicle. The vehicle may either be a ferry for hauling conventional automobiles and trucks, or it may be a special purpose vehicle that carries cargo and/or passengers. The vehicle has wheels that roll on tracks located within the shrouds. The vehicle may be powered electrically or by other means.
One factor that limits the speed of such a system comprises the rolling components, which create friction. Prior art exists that employ permanent magnets located on the undersides of components of a train. These magnets are placed in proximity to a series of separate, individually wound coils of copper wire that are mounted adjacent to the tracks. The copper wire is wound at a 90xc2x0 angle to the direction of the train travel.
As the train is moved along the rails, the magnetic fields of the permanent magnets pass through the coils of copper wire. This induces currents in the coils that in turn produce opposing magnetic fields to the permanent magnets. This causes the permanent magnets to be repulsed from the coils, thereby levitating components of the train above the rails. Additional coils are also located at the sides of the rail system. The train components have permanent magnets mounted at the sides in such a manner to interact with the coils at the sides, thereby providing horizontal direction control for the vehicles.
The prior art systems have disadvantages. Magnetic levitation systems cannot be used in railway switching areas, making it necessary for vehicles to slow to a low speed and exit the magnetic levitation segments of the rails for track-to-track switching by conventional railroad means. The magnetic levitation coils are added to the outsides of the conventional railway rails, thereby requiring a railway bed of greater width than conventional railroads. These railways have been expensive to build because of extensive land grading and/or massive structural supports for heavy elevated railways. Also, they are expensive because of the large number of separate, individually wound coils of copper wire that form the magnetic levitation rails.
The transport system of this invention uses a pair of levitating rails. Each levitating rail has a core and a plurality of coils extending circumferentially around the core perpendicular to the length of the levitating rail. Also, each of the levitating rails has an upper surface located directly above the core. A vehicle used on the transport system has wheels that roll on the upper surfaces of the levitating rails while at a low speed. The vehicle has a plurality of magnets which create magnetic fields that pass through the coils while the vehicle moves along the levitating rails. This induces in the coils, which causes magnetic fields to be generated that repel the magnetic fields of the permanent magnets. Once the speed begins to pick up, the levitating rails will levitate the vehicle.
Each of the levitating rails has a hollow core that is nonmagnetic. The vehicle may be powered along the guideways by various systems, with one of them being a linear motor. The linear motor comprises power coils periodically spaced apart from each other along the length of the rails. The power coils are supplied with alternating current, which induces movement of the vehicle when its magnets react with the magnetic fields produced by the power coils.
Also, a steering rail is mounted adjacent to at least one of the levitating rails. The steering rail has a plurality of coils wrapped around a core. A pair of steering magnets are mounted to the vehicle and positioned on opposite sides of the steering rail. The steering magnets create magnetic fields that pass through the coils of the steering rail. This induces current in the coils, which causes magnetic fields to be generated that repel the magnetic fields of the permanent magnets. The opposing forces created by the magnets and the coils steer the vehicle by tending to cause the permanent magnets to remain substantially equidistant from the steering rail.
Preferably, there are steering magnets mounted to the vehicle on each side of the vehicle. In a switching area, steering rails are located in both guideways. One of the steering rails passes straight through the switching area for retaining the vehicle on a main track. The other steering rail diverges off into a branch line. If the vehicle is to be switched onto the branch line, an actuator on the vehicle causes the steering magnets on the main track side to move downward from the main track steering rail. At the same time, another actuator on the vehicle causes steering magnets on the branch side to be moved upward into proximity with the branch side steering rail. The branch side steering magnets will thus cause the vehicle to follow the branch rail, resulting in the vehicle exiting from the main track onto the branch line.
Preferably the steering rail is formed by providing sheets of substantial width. Each sheet, which may be of an insulating film such as Mylar, will have parallel traces of conductive strips formed on it. The conductive strips will be separated by insulation strips, which are air gaps between the strips. The sheet is wrapped in multiple wraps around the core to create multiple coils along the rails simultaneously. For use as a levitating rail, these coils will be shorted at each wrap so that each coil forms only a single loop.